In recent years, for THz wave band (0.1 THz to 10 THz) positioned in intermediate frequencies between electromagnetic waves and light waves, studies of applicabilities of ultra high-speed wireless communications, sensing, imaging, etc. have become active, and there has been expected its practical application. However, since THz-wave systems are composed of large-sized and three-dimensional structured components under the current circumstances, large-sized and expensive configurations are required for such THz-wave systems. In order to miniaturize the whole of such systems, implementation of THz-wave integrated circuits (ICs) integrating devices is indispensable.
Utilization of technologies of both of a light wave region and an electric wave region can be considered as fundamental technologies of the THz-wave ICs. However, optical components, e.g. lenses, mirrors, are composed of large-sized and three-dimensional structured components, and therefore are not suitable for the integration. Moreover, it is becoming difficult to produce hollow metal waveguides used in the electric wave region due to its fine three-dimensional structure. Furthermore, a waveguide loss in planar metallic-transmission lines is increased as effect of metallic absorption is increased.
As a fundamental technology of THz-wave ICs, there has been studied applicability of a two dimensional photonic crystal (2D-PC) slab where outstanding progress is seen in the light wave region (e.g., refer to Non Patent Literatures 1-3.).
On the other hand, it is also proved that such a 2D-PC slab can capture THz waves incident from the outside by utilizing an in-plane resonance effect in a 2D-PC photonic band edge (for example, refer Non Patent Literature 4.).